<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>story</title>
    <style>
        div{
            overflow: hidden;
            width: 200px;
            height: 200px;
            border: 1px solid pink;
            margin: 100px auto;
        }
        div::before {
            content: "加油";
            display: block;
            width: 100%;
            height: 100%;
            background-color: rgb(0, 255, 255);
            transform-origin: left bottom;
            transform: rotate(180deg);
            transition: all 0.2s;
        }
        div:hover::before{
            transform: rotate(0deg);
        }
    </style>
</head>
<body>
   <div></div> 
</body>
</html>